Thermoelectric materials are known that convert thermal energy directly into electrical energy or vice versa. The efficiency of a thermoelectric material is characterized by “The Thermoelectric Figure of Merit,” which is defined as the square of its Seebeck coefficient times its electrical conductivity divided by its thermal conductivity. The Seebeck coefficient is a measure of the “thermoelectric pumping power”, i.e. the amount of heat that a material can pump per unit of electrical current. The electrical conductivity is a measure of electrical losses in a material, and the thermal conductivity is a measure of heat that is lost as it flows back against the heat pumped by a material.
A relatively high-efficiency thermoelectric material has been proposed that includes PbSeTe/PbTe quantum dot superlattice (QDSL) structures. The combination of a relatively larger power factor with low lattice thermal conductivity provides a significant increase in the thermoelectric figure of merit for these QDSL structures compared to their bulk alloys. The proposed QDSL structures are prepared using molecular beam epitaxy or MBE. U.S. patent application Ser. No. 10/808,180, filed Mar. 24, 2004, incorporated herein by reference, describes a methodology for producing bulk PbTe-based structures having useful thermoelectric properties. The PbTe structures are prepared by grinding PbTe material to form a powder, and pressing and sintering the powder. The resulting sintered microstructure was found to contain nanometer-sized grains that enhanced the thermopower, which was attributed to the selective scattering of electrons depending on their energy.
While the aforementioned thermoelectric material exhibits an enhanced Seebeck coefficient, there exists a need for still further improvement in the thermoelectric performance of materials produced by bulk processes. Moreover, it is desired to provide a method for manufacturing thermoelectric materials that does not require powder methodology.